标题：Designed synthesis, morphology evolution, and enhanced photoluminescence of a highly efficient red dodec-fluoride phosphor Li3Na3Ga2F12:Mn4+ for warm WLEDs

Abstact：Red phosphors of Mn4+ doped dodec-fluorides Li3Na3Ga2F12:Mn4+ (LNGF:Mn) with various morphologies have been synthesized from K2MnF6, LiF, NaF, and Ga2O3 in HF at room temperature with excessive LiF and NaF relative to the stoichiometric composition in LNGF:Mn. The formation mechanism of the red phosphor LNGF:Mn has been discussed based on detailed experimental results compared with the identified phosphor Li3Na3Al2F12:Mn4+ (LNAF:Mn). The optical properties of LNGF:Mn have been systematically investigated compared with the red phosphors Li3GaF6:Mn4+ (LGF:Mn), Na3GaF6:Mn4+ (NGF:Mn), and LNAF:Mn in detail. It is observed that the as-obtained phosphor LNGF:Mn exhibits superior properties in chromaticity coordinates and a high luminescence efficiency with a strong potential in enhancing the performance of solid-state lighting. The HF-concentration-dependent morphologies of the phosphor LNGF:Mn have been investigated by scanning electron microscopy (SEM). The luminescence of the phosphor LNGF:Mn has been enhanced by optimizing the synthetic parameters, such as the concentrations of HF and K2MnF6. The white light-emitting diode (WLED) encapsulated with the as-obtained red phosphor LNGF:Mn and commercial yellow one Y3Al5O12:Ce3+ (YAG:Ce) on a GaN chip produces a warm white light with a color rendering index (CRI) of 91.32 at a correlated color temperature (CCT) of 3986.08 K.

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